The Effects of Absorbent Temperature and Flue Gas Impurities on Carbon Dioxide Absorption in Carbonate Solutions


Brett Spigarelli, Mark Preston, and Jacqueline Walitalo

Capture of carbon dioxide (CO2) from fossil fuel burning power plants is considered a logical target for mitigation of anthropogenic CO2 emissions. Chemical absorption via carbonate solutions has been proposed as a possible CO2 mitigation technology. Fossil fuel burning power plants present unique challenges to CO2 capture, such as elevated flue gas temperatures (may lead to heating of the solution) and the presence of impurities (NOx and SOx) in the flue gas which may degrade the solution. Unlike the commercially available amine absorption technology, carbonate solutions may be able to act as a multi pollutant capture system. Carbonate solutions could serve as a cheap outlet for other impurities such as NOx and SOx which have their own dedicated, and costly, removal systems. In the present work, the absorption of CO2 into a 2% (w/w) sodium carbonate solution was studied at solution temperatures from 25 °C to 60 °C and with gas streams containing a mixture of CO2, NOx, SOx, and N2. The goal of the study was to assess the potential/performance of carbonate solutions as a multi pollutant control technology at fossil fuel burning power plants. Studies found that when the solution temperature was increased from 25 °C to 60 °C, roughly a 50% decrease in the CO2 absorption rate was seen. This implies that the solution should be kept as cool as possible for absorption. Absorption of carbon dioxide in the presence of NOx and SOx revealed a slight decrease in both the CO2 absorption capacity of the solution and the rate of CO2 absorption into the solution. However, these negatives were offset by the complete capture of all the NOx and SOx that was fed to the solution. Current studies suggest sodium carbonate solutions possess the potential to serve as a multi pollutant capture technology at fossil fuel burning power plants.



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